The present invention relates to sawmills, and more particularly to the provision of a sawmill which has power-actuated mechanisms for loading a log onto the mill, clamping the log to the mill, rotating the log about its axis, and levelling the log on the mill.
Sawmills of the type for which the improvements of the present invention are provided are well known in the art. One such sawmill is disclosed in U.S. Pat. No. 4,559,858 issued Dec. 24, 1985. Such sawmills can comprise elongated track means, platform means for supporting a log or other wood to be cut adjacent the track means, a carriage movable longitudinally along the track means past the platform, and cutting means, such as a band saw, mounted on the carriage to cut the log as it passes over the platform.
It will be clear from prior U.S. Pat. No. 4,559,858 that such sawmills illustratively may be relatively light weight as compared to larger rotating blade sawmill machines used in permanently-located commercial sawmills. The illustrative sawmill improved by the present invention is a portable sawmill, illustratively trailer-mounted or wheel-mounted, which may be pulled behind a truck or tractor directly to the timber to be cut. Round logs may be sliced into planks in the forest so that only the planks have to be hauled out in a truck to save trucking expense.
Heretofore, many such portable or relatively small sawmills have typically been constructed such that the logs have been manually loaded onto the sawing platform, manually clamped in place on the platform and, if necessary, manually rotated about the log axis to square up the log in cross section, i.e., produce a cant.
The sawmill of the present invention is, comparatively speaking, a production sawmill with improved power-loading mechanisms, power-clamping mechanisms and power-rotating mechanisms. The primary driver or power unit for such a sawmill is the illustrative gasoline engine on the band saw carriage which drives the band saw. This gasoline engine may also be used to drive an electrical generator to provide the necessary electric power required by the system of the present invention. Just how this is accomplished within the present invention will be described hereinafter.
The present invention, therefore, is a sawmill comprising elongated track means, platform means for supporting a log adjacent the track means, a carriage movable longitudinally along the track means past the platform means, cutting means mounted on the carriage to cut the log on the platform means and means for loading the log onto the platform means. Illustratively, the sawmill may also include means for clamping the log to be cut on the platform means, means for rotating the log about its axis on the platform means so that the log can be squared in cross section, and means for levelling the log on the platform.
In the illustrative embodiment, the loading means, clamping means, rotating means and levelling means are all hydraulically actuated by a hydraulic power pack including an electrically-driven motor and a hydraulic pump, reservoir, valves and tubing as required. Each of the loading means, clamping means, log-rotating means, and levelling means is driven by a hydraulic motor or hydraulic cylinder and piston arrangement controlled by the power pack. The power pack, of course, includes the necessary valve means for coupling pressurized hydraulic fluid from the pump to the hydraulic motors to drive the hydraulic motors, i.e., extend and retract the hydraulic cylinders.
In the present invention, the loading means includes log-engaging means movable toward and away from the platform, ground-engaging means for engaging the ground and means for driving the log-engaging means toward and away from the platform. The driving means acts between the log-engaging means and the ground-engaging means. As indicated above, the driving means may illustratively be a hydraulic motor or hydraulic cylinder and piston assembly controlled by the power pack. In the present invention, the loading means comprises arms pivotally mounted to the platform to serve as the log-engaging means and ground engaging legs also pivotally mounted to the platform to serve as ground-engaging means. The drive means or hydraulic cylinder means acts between the log-engaging arms and the ground engaging legs so that the weight of the log is actually supported on the ground when a log is being lifted to the platform. This feature permits loading of heavy logs without requiring the platform or entire sawmill to be stabilized by heavy outriggers. Further, the arms and legs are pivotally movable to a nonuse storage position above the platform for storage and transit.
Further, the sawmill of the present invention comprises means for actuating each of the log-handling means, i.e., loading means, clamping means, rotating means, and levelling means, and means for interlocking the aforesaid driving means, e.g., the hydraulic cylinders, to the actuating means to allow the actuating means to actuate the driving means only when the sawmill carriage is in a predetermined position along the track means. In the illustrative embodiment, for instance, the predetermined position along the track means is the proximal end or near proximal end of the track means. At that predetermined position, the electrical power system on the band saw carriage provides power to the aforedescribed power pack so that the various log-handling means can be manipulated while the carriage is at that predetermined position. It will be appreciated, therefore, that the various log-handling means will not be movable when the carriage is away from the predetermined position.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.